Backing off mechanism for grinding machines



Dec. 8, 1931.

E. A. WALKER ET AL BACKING 'OFF MECHANISM FOR GRINDING MACHINES Filed July 27 1929 4 Sheets-Sheet :ilii

Dec. 8, 1931. E. A. WALKER ET AL BACKING OFF MECHANISM FOR GRINDING MACHINES Filed July 27, 1929 4 Shetsheet 2 a azzb Dec. 8, 1931. E. A. WALKER ET AL 1,835,733

BACKING OFF MECHANISM FOR GRINDING MACHINES Filed July 27, 1929 4 Sheets-Sheet 3 6 )2 when v- M 4 Sheets-s E. A. WALKER ET AL BACKING OFF MECHANISM FDR GRINDING MACHINES Filed July 27, 1929 a \N @QN Patented Dec. 8, 1931 unirno S AT S PATENT- OFFIV'CVEM v ERNEST A. WALKER Ann HARvEY M. Anms'on, orwonons'rnnymssnonnsnrrs,

nssrenons :ro JOHN BATH, or WORCESTER, MASSACHUSETTS r BACKING- orr MECHANISM FOR "GRINDING MACHINES;

Application filed July 27,1929. Serial'No. 381,568. 2

This invent-ion relates particularly to grinding machines adapted for the production of ground taps and other similar work.

It is the general object of 'ourinvention to provide improved mechanism in such .a grinding mashing-by which the teeth-of a tap or other similar article may be conveniently and accurately backed off or relieved to provide a desiredclearance.

In the preferred form, our improved backing ofl mechanismis actuated'by an eccentric to positively advance the grinding wheel toward the work and to alternately and positively withdraw the wheel therefrom.

Our invention further relates to arrangements and combinations of partswhich will be hereinafter described and more particularly pointed out in the appended claims.

A'preferred form of our invention is show in the drawings in which v i Fig. 1' is a side elevation, partly in section, showing our improvements applied to a grinding machine; 2

Fig. 2' is a plan view of the backing off or relieving attachment, with certain parts shown in section; I

Fig. 3 is a detail left hand side elevation of certain parts, looking in the direction of the arrow 3 in Fig. 2; f

Fig. 4 is a detail-sectional sideelevat-ion, taken'along the line 44 in Fig. 2 v

Fig. 5 is a plan view of an eccentric shaft; Fig. 6 is a plan viewof an eccentric sleeve;

Fig. 7 is a planview of an adjusting eleupon centers,the headcenter 46 being shown ment cooperating with said sleeve;

Fig. 8 is a right hand side elevation showing the connections from-the eccentric to the grinding wheel slide; i

Fig. 9 is a front-elevation of certain parts shown in Fig. 8; V V

Fig. 10 is a detail plan view, looking, in the directionof the arrowlOin Fig. 9;

Fig. 11 is a sectional rear elevation, taken I along the line 11- 11 in Fig.1; and v Fig. '12, is a plan view of certainparts to be described. I

Referring to the drawings, we have shown portionsof a grinding machine particularly adapted to the production ofground taps and other similar threadedwork. The grinding reciprocated during the machine'shown in the drawings comprisesa base or frame 20 (Fig. 1) on which a wheel table or carriage 21" is mounted for sliding movementaxially of the grinding wheel W.

Thewheel- W is mounted on a Wheel shaft 22, rotatable in hearings in a wheel head 23, which in turn is mounted in transverseguideways on a cross slide 25.

A nut 26' (Fig. is mounted on a bracket 27 projecting upward from the cross slide '25 and an adjustingscrew 28 is threaded in the nut 26. The screw 28 is rotatable in bearings in the wheel head 23, but is held from relative axial movement therein; Y s

A hand wheel (not shown) is mountedon a shaft 30 having bearings on the wheel head 23 and projecting forwardly above the wheel and work. The shaft 30 is connected by spiral gears 31andbevel gears 32 to the adjusting screw 28. By these connections theg'wheel head 23 maybe manually adjusted forward or rearward on the'cross slide 25. The Wheel W is rotated by a belt B which is guidedto a'iidfrom the wheel pulley 34 by guide pulleys 35 and 36. l

The cross slide 2'5'and thecarriage or table 21 are provided with guide'bars 4O and ll Fig. 11) respectively, which guide bars are formed with V-shaped'guideways 42, re-

versely disposed and adapted to receive balls.

44 on which the cross slide is movable for- Ward and rearward with very slight resistance. p

The work K (Fig. 2) may be supported mounted in a work head 49, supported on a work table 50, which may be automatically by any suitable mechanishi.

We will now describe themeohanism by which the relieving or backing off movement of the grinding wheel is produced.

' 'A'hollow shaft or casting mist mounted on cone bearing members 58, one at,

each endthereof, said members being secured in supporting brackets 54 (Fig. '8) projectrindi'ng operation Y em ing forwardly from the front end of the table or carriage 21. A shaft or rod (Fig. 9)

extends through the hollow shaft 52 and is provided with nuts at each end by which the conical bearing members 53 may be adjusted relative to the shaft 52 so thatalljback lash will beeliminated while the shaft is left free to turn. I

An arm 57 projects upward from the shaft '52 and is provided with cross rod 58 extending through slots or openings 59 in spaced arms or brackets60 projecting forward from the cross'sl'ide' 25.

65.v The "shaft 52 and "the arms '57 and 62 m-ay conveniently be formed as asingle casting.

The eccentric connector 64 (Fig. 2) isjprovlded with a bushing 66 to receive an eccentric sleeve 68".(Fig. 6), which in turn is a mounted on'i'the eccentric portion 69 of a shaft 70. The shaft .70 is rotatable inbear- -ings 71secured to stand or bracket 72' (Fig. 1 8) which in turn is bolted .to the wheel table 21 and is thus maintained in fixed transverse position. r

The eccentric sleeve 68 is provided with a notched flange-74 anda serrated end portion 75. A collar 77 (Figs. 2 and 7) is keyed to the eccentric portion 69 of the shaft and ie-provided with a serrated face 7 8. The serrated face 78 of the collar 77 may be forced "against the serrated face? 5 of the-eccentric sleeve 68 by an adjusting nut-78 (Fig. 2). v By changing the relative angular relation I of the eccentric sleeve 68 to the eccentric portion 69 ofthe shaft 70, the eccentricity of the outer bearingsurface of the sleeve 68 may be -varied within substantial limits; The parts maybe so adjusted that the surface 68 will be concentriewith the axis of the shaft 70 or they may be so adjusted that any desired eccentricity within reasonable limits will be produced.

When it is desired toadjust the eccentricity, the-nut 78 is screwed outward,-thecol- Y hr 77 is withdrawn, and the eccentricsleeve '68 may then be turned by applying a spanner'wrench to the notched disc 7 4 The end ofa square shaft 80 (Figs. 2 and is received in a slot 81 (Fig- 5) formed .-in the head 82 of the shaft 70. A'cylindrical extension83 ofthe-shaft 80 is received in an opening 84 in the head 82 and may be secured therein by a cross pin 85. f j

" The square shaft 80 extends through a wide facedgear 87 (Fig. 2) having hubportions 88 supported in bearingsin a bracket -90 extendingrearward from the workdriv- ,inghead, 49. The work spindle 47 is connected to continuously rotate the'square-shaft the springs may be adjusted by moving the 80 through a pair of spur gears 91 and 92 (Fig. 2), an intermediate shaft 93, a gear 94: mounted thereon, an intermediate gear 95 (Fig. 3) mounted on an angularly adjustable bracket 96, an intermediate pinion 96 also mounted on the bracket 96, and a change gear 97 engaging the wide'facedgear 87. The bracket 96 is held in position by bolts 98 extending through slots 99 which permit limited angular adjustment of the bracket.

' Through the connections above described, the eccentric shaft 70 and sleeve 68 mounted thereon are continuously rotated from the work spindle 17, while the sliding connection of the square shaft 80 with the gear 87 per- 30 mits relative axial movement of the work head and eccentric shaft.

The eccentric. sleeve 68 acts through the eccentric connector or link 64 to oscillate the shaft 52 and the, arm; 57 formed thereon.

Such movement of the arm 57 is directly communicated-tothe cross slide 25 andcauses a reciprocating movement thereof which is positive in both. directions.

This movement, while positive, is of very slight extent and is commonly-limited to a few-thousandths of an inch in each direction.

movements ofthe cross slide to be magnified "and visibly indicated by a pointer 103 on a suitablescale 104.

In order .to prevent any lost motion or chatter of the parts, we have provided a spring 110 (Fig. 8) connected to the arm 62 and tending to take up any back lash in the connections between the arm 62 and the eccentric sleeve 68.

We have also provided springs 112 (Fig:

' 12) to take up any back lash in the connections between the cross slide 25 and the oscillating arm 57. For this purpose we provide rods 1'14 extending rearward from the table 21 and provided with a cross bar to which the rear ends of the springs 112 may be attached. The opposite ends of thesprings are secured to the cross slide 25. The tension of cross bar 115 forward or rearward by nuts 117 on the threaded rear ends of the rods 114,

Having thus descibed our invention and the method of operation thereof, it will beseen that we have provided means for positively reciprocating. the cross slide 25 and that we have provided means for conveniently and positively adjusting the extent of the ,reciprocating movement, said latter meansezuo grinding wheel, a wheel supporting headv comprising toe eccentric sleeve 68 mounted on the eccentric portion 69 of the shaft 70.

The eccentric is continuously driven in exact timed relation with the rotation of the work K and commonly gives the grinding wheel several backing revolution of the work K. v I

It is found by actual test that our improved backing ofi' mechanism will produce extremely accurate results so that the backing off may begin closely adjacent the cutting face of the teeth, whereas with certain devices previously used the Variable operation of the relieving attachment made it impossible to start the backing off close to the cutting edge.

Our device is operable at high speed and runs very smoothly and without any jar or vibration.

An important advantage in the use of an eccentric drive in our improved relieving mechanism arises from the fact that the mechanism operates equally well with the eccentric rotating in either direction. Accordingly, the work spindle may be reversed for grinding in the opposite direction and the teeth will be relieved as before. The invention is also applicable to the grinding of both right and left hand threads without any eccentric or gearing.

We claim 1. In a grinding machine, means to support and rotate a piece ofv work, a grinding wheel, said work and wheel being mounted for relative axial movement, means to rotate said wheel, and means effective to alternately positively advance and positively withdraw,

the wheel toward and from the work in timed relation to the rotation of the work, said means including a rock shaft, an arm on said shaft, a continuously rotating eccentriccircular disc, a link pivoted on said eccentric disc and pivotally connected to said arm, a sliding support for the grinding wheel and a seeoff movements for each 5. In a grindingmachine, means to support and rotate a piece of work, a rotatable grinding wheel,a wheel table mounted for adjustment axially of the work, a wheel head mounted on said table for movement transversely of the Work, a rock shaft on said table connected to reciprocate said wheel head, an eccentric, operating connections between said eccentric and said rock shaft, and means to rotate said eccentric in timed relation to the rotation of the work. I

6. The combination in a grinding machine as set forth in claim 7 in which said latter means is operatively connected to the work rotating means in every axial position of the work relative to said grinding wheel.

7. In a grinding machine, means to support and rotate a piece of work, a grinding Wheel, said work and wheel being mounted for relative axial movement, means to rotate said wheel, and means to alternately advance and withdraw the wheel toward and from the work in timed relation to the rotation of the work, said latter means including a rotat ing actuating member operative to produce the same movements of the wheel head and at the same relative speeds when rotated in either direction.

In testimony whereof we have hereunto affixed our signatures.

ERNEST A. WALKER. HARVEY M. ALLISON.

0nd arm on said rock shaft connected to said support.

2. In a grlndmg machlne, means to support and rotate a piece of work, a grinding wheel, said work and wheel being mounted,

for relative axial movement, means to rotate said wheel, means to alternately advance and withdraw the wheel toward and from the work as the wheel and work are rotated, and

multiplying means to indicate on an enlarged scale the extent of such forward and rearward movements.

3. In a grindmg machine, means to support and rotate a p ece of work, a rotatable mounted to slide toward and from the work,

an eccentric rotated in timed relation to the 

